Method of and device for detecting temperature changes in heating or cooling tubes, coils, etc.



y 1932- H. 'r. DARLINGTON 1,858,293

IETHOD OF AND DEVICE FOR DETECTING TEMPERATURE CHANGES IN HEATING OR COOLING TUBES, COILS, ETC

Filed April 25. 1927 Patented May 17, 1932 UNITED STATES PATENT OFFICE v HOMER T. DARLINGTON, OF WEST CHESTER, PENNSYLVANIA, ASSIGNOR, BY MESN'E ASSIGNMENTS, TO OIL CORPORATION OF'AMERICA, A CORPORATION OF DELAWA METHOD OF AND DEVICE FOR DETECTING TEMPERATURE CHANGES IN HEATING: O

COOLING TUBES, COILS, ETC.

Application filed April 25,

My invention relates to a method of and device for detecting a substantial rise in the temperature of any one or more of several heating tubes within a fire box or furnace or other means of heating or a substantial decrease in the temperature of cooling coils or the like. While of very general application, my invention is specially designed to give notice of the overheating of tubes used in the distillation or cracking of petroleum 011, such as not infrequently occurs when carbon accumulates in a tube during oil cracking. It is not, however, limited to that use, but may be advantageously used on heating or cooling tubes, or other like apparatus, for whatever purpose employed, where it is desirable that notice shall be given if an increase in temperature above a predetermined degree, or of similar fall in temperature.

In the drawing, 1 and 3 are headers or. chambers connected by a plurality of heating tubes 2 which are heated by any suitable means. These represent a section of an oil cracking still, and may be a part of any apparatus used for any purpose, in which are heating tubes such as are here shown. The form and component parts of such an apparatus will, of course, vary and the type illustrated is shown merely to indicate how my device is applied.

4 is a source of electric current, one terminal of which is directly connected to header or chamber 3 by conducting wire 5, or other suit able electrical conductingme ans,the other terminal being suitably connected through recording means or device 6, and electrical indicating means or device 7, with rotating commutator 8 which is driven continuously o intermittently by driving means 9.

The rotating commutator 8 is provided with a plurality of terminals 10 one for each tube or other like means whose change in temperature is to be observed. Each of these terminals 10 is connected through variable re-. sistance means 11 by a wire 12 or other suitable electrical conductor with one of the tubes 2 at or at about a point 13 midway between its two ends.

Variable resistance means 11 are provided so in each of the conductors 12 for the purpose 1927. Serial no. 18am.

ofregulating the deflection of the indicating arm in electrical indicating means 7 and in electrical recording means 6 at the instant when said resistance means is in electrical connection with said indicating means through rotating commutator 8 so as to normalize the indication of electrical current, under conditions of temperature normally in and surrounding the tube, coil or the like, with which it is in connection. Conductors 12 attached to the tubes 2 may be composed of Invar or other suitable material the electrical conductivity of which will not be substantially affected by heat from the tubes, fire box, etc.

In practice, the operation is as follows: When the apparatus is first put under fire and the tubes 2 are known to be sound and clean on the inside, each individual resistance 11 is so adjusted as to show a normal indication of current by means of the indicator 7, as well as by the recording means 6. The voltage of source of current 4 is preferably controlled by means of rheostat 14 so that the voltage across the system is maintained substantially constant.

Under the above conditions, just as long as the interior of each one of the circulating tubes 2 remains substantially clean and free from any material obstructive to the flow of circulating oil within said tube, the rheostat 14 being normalized, the movement of the'recording arm on recording means 6 will lie within clearly defined limits. But as soon as a material change in the interior condition of the circulating tube causes such a reduction in the flow of oil within the tube, that the cooling effect of said oil is insufficient to extract heat in normal quantity from a tube, the temperature of the oil in that tube will rise and likewise the temperature of the tube itself will rise. This rise in temperature of the tube will, on account of the electrical properties of the material of which it is made (usually iron or steel) cause a decrease in the current conductivity of the tube, and, therefore, a corresponding reduction in the current through the ends of the tube to the middle point 13 of the same, at which point the conductor 12 is thereto connected.

The de osits made when oil is treated are largely, i not entirely, of carbon; the electrical resistance of which decreases with increased temperature, but its initial resistance is so much higher than that of any metal which might be used in tubes or coils, and its decrease in resistance on heating is relatively so small that there is always a large diflerence in resistance in the two materials at any temperature it is possible to employ.

Each time the rotating commutator 8 makes electrical connection between this overheated tube and recording means 6 the movement of the latters indicating arm will, because of the reduced current, be less than the movement of the indicating arm when in contact with any other one of the circulating tubes which then remains at a normal temperature. .On systematic inspection, at reg ular intervals or by means of alarms, this reduced movement will soon be apparent, and by disconnecting the rotating commutator 8 from its driving device 9, and turning the commutator by hand, while observing the instantaneous deflections of electrical indicating means 7, the terminal of the conductor leading to the faulty circulating tube may be located at most by one revolution of the contact point of the commutator 8. This terminal, being identified at the time of installation with the corresponding tube as indicated on a diagram or by other suitable means, will clearly show, not only a dangerous condition of one or more of the circulating tubes 2, but also the exact identity and location of each of the faulty tubes.

While I have described and shown but a single embodiment of the invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made which do not depart from the spirit and scope of the invention as disclosed in the appended claims.

I claim:

1. The method of indicating the thermal conditions of a series of heated tubes-consisting of passing an electric current through each of said tubes in succession one at a time and measuring sal-d current whereby undue heating of any tube is apparent.

2. The method of indicating the thermal conditions of a series of heated tubes consisting of passing an electric current in both di rections from the center of each of said tubes in succession one at a time and measuring said current whereby undue heating of any tube is apparent.

3. In an apparatus of the class described, headers, a series of tubes connecting said headers, and an electrical circuit of which each tube may selectively form a part, said circuit including means for showing the strength of current passing through each tube and thereby indicating the thermal conditions thereof.

4. In an apparatus of the class described, headers, a series of tubes connecting said headers, a lead connected to each tube, a distributor having a series of terminals, each terminal being connected to one of said leads and a brush adapted to make contact with each of said terminals in succession, a current indicating means, and a source of current in series circuit with said brush and oneof said headers whereby the current flowing through each tube is successively shown as a source of current in series circuit with said brush and one of said headers whereby the current flowing through each tube is shown as the brush is moved over the terminals.

HOMER T. DARLINGTON. 

